docs: def group(self):
          """
          The group this event belongs to.  Adding the event as a child of a
          group automatically assigns the event to that group.
          """
          retval = None
          parent = self.get_parent()
          Group = get_group_model()
          if issubclass(parent.specific_class, Group):
              retval = parent.specific
          if retval is None:
              retval = self.group_page
          return retval